routes: add boleto routes to express app

[evaporei]

Description

Adapt lambda handlers which were used as routes to work on the express web server.

Add default handlers for the /boletos resource and add a default handler for any other routes and methods.

This closes https://github.com/pagarme/ghostbusters/issues/10 (internal issue)

Your checklist for this pull request

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1. I've read the project's Contributing Guidelines
2. My commits are well written and follow pagarme/git-style-guide
3. My changes are well covered by tests and logs
4. I've updated the project docs (if needed)
5. I fell safe about this implementation
6. I feel comfortable with the code I wrote, and I'm not ashamed to show it to my friends

In a good pull request, everything above is true :relaxed:

this closes https://github.com/pagarme/ghostbusters/issues/10